<template>
  <div>
    <el-upload
      :on-preview="handlePreview"
      :on-remove="handleRemove"
      :on-exceed="handleExceed"
      limit="1"
      accept=".xlsx, .xls"
      @on-change="handleFileChange"
      :file-list="fileList">
      <el-button :loading="loading" type="primary">模版导入</el-button>
    </el-upload>
    <!--<input id="excel-upload-input" type="file" accept=".xlsx, .xls" class="c-hide" @change="handleFileChange">-->
  </div>
</template>

<script>
  import XLSX from 'xlsx'

  export default {
    data() {
      return {
        loading: false,
        excelData: {
          header: null,
          results: null
        }
      }
    },
    methods: {
      generateDate({ header, results }) {
        this.excelData.header = header
        this.excelData.results = results
        this.loading = false
        this.$emit('on-selected-file', this.excelData)
      },
//      handleUpload() {
//        document.getElementById('excel-upload-input').click()
//      },
      handleFileChange(e) {
        this.loading = true
        const files = e.target.files
        const itemFile = files[0] // only use files[0]
        const reader = new FileReader()
        reader.onload = e => {
          const data = e.target.result
          const fixedData = this.fixdata(data)
          const workbook = XLSX.read(btoa(fixedData), { type: 'base64' })
          const firstSheetName = workbook.SheetNames[0]
          const worksheet = workbook.Sheets[firstSheetName]
          const header = this.get_header_row(worksheet)
          const results = XLSX.utils.sheet_to_json(worksheet)
          this.generateDate({ header, results })
        }
        reader.readAsArrayBuffer(itemFile)
      },
      fixdata(data) {
        let o = ''
        let l = 0
        const w = 10240
        for (; l < data.byteLength / w; ++l) o += String.fromCharCode.apply(null, new Uint8Array(data.slice(l * w, l * w + w)))
        o += String.fromCharCode.apply(null, new Uint8Array(data.slice(l * w)))
        return o
      },
      get_header_row(sheet) {
        const headers = []
        const range = XLSX.utils.decode_range(sheet['!ref'])
        let C
        const R = range.s.r /* start in the first row */
        for (C = range.s.c; C <= range.e.c; ++C) { /* walk every column in the range */
          var cell = sheet[XLSX.utils.encode_cell({ c: C, r: R })] /* find the cell in the first row */
          var hdr = 'UNKNOWN ' + C // <-- replace with your desired default
          if (cell && cell.t) hdr = XLSX.utils.format_cell(cell)
          headers.push(hdr)
        }
        return headers
      }
    }
  }
</script>

<style scoped>
  #excel-upload-input{
    display: none;
    z-index: -9999;
  }
</style>
